I have done the exact opposite... I went from the flat side to the round style, also changed the starter cover. Much more for the retro old look; had to change the right side plastic carb to aircleaner pipes. Looks just like the /6.

It shouldn't be a problem to do this, but a little complicated. You'll need the airbox and top, an '80-'95 starter cover, crankcase vent hoses and breather centering devices. You'll also have to do something about choke operation; the later bikes have a different left handlebar perch and 2 into 1 cable. To do this will require different carb tops so the chokes can be closed with a spring. The other option would be to cut your old choke cables and turn them into manually pulled items-I would think this a pain.

I'd rather open up the old clamshell housing. I used to drill them as the R90S and other sporty twins, but lately have cut a huge window in the rear of the box. Gives a nice induction roar.

I like what they do for the tune too. I think they are easier to service and work around too. The tops are still cheap. Get both types and see which one works better for you. My bike is making WAY more power than stock and I still use the one small/one large horn setup for a lot stronger midrange with my setup. Crank vent? I recommend the stock hose to the box. From there, slide a 3/8ths auto fuel line into the stock hose and snake it between the stacks to a firewall junction inserted into the drain hole. I drill the firewall junction for maximum ID. Then I get another section of 3/8ths fuel line and run that from there to where ever you want. As I always advise, be careful not to get oil on your back tire if you run it out back or where ever. I use a modified K+N. Performance? I use them because, properly maintained, they filter a LOT better than the stock filters despite what you may read about them on the net. Looks? IMO, what works good looks good. I like the looks of the later box.

Thanks for the post. I've bought the newer model complete airbox from an Ebay seller. Should have it in a week or so and will fiddle with it. Since I've never had the later bike I'm not sure how the box is oriented...where do the horns face? Forward, back, ...? Anybody have a pic?

Do they perform better? I think I've heard that they do but can't see there being any reason for them to perform better. Those air horns don't stick into the wind to provide any ram effect I think. I've always thought ram effect was over rated any way.

It would be nice to evenly distribute the blow-by gases instead of dumping them all into the right carb.

Do they perform better? I think I've heard that they do but can't see there being any reason for them to perform better. Those air horns don't stick into the wind to provide any ram effect I think. I've always thought ram effect was over rated any way.

It would be nice to evenly distribute the blow-by gases instead of dumping them all into the right carb.

Drilled clam shells for the most part will get you higher peak power. Square boxes for the most part will get you to peak faster. It all depends on your priorities.

Velocity stacks prefrer still air, not ram air. Two completely different subjects.

The press and BMW claimed that the square airbox crank vent setup evenly distributed crank vent oil to both cylinders. It does not. They almost entirely favor the left side. Why and how? The vent hose to the left velocity stack does not rise up quite as high as the one for the right stack. It's like plumping: Shit won't go up hill. Yes, I know BMW and the press claimed the late model setup distributes the oil evenly but they don't in fact. Yes, I know ss is about the only source for this info but it is still true.

Drilled clam shells for the most part will get you higher peak power. Square boxes for the most part will get you to peak faster. It all depends on your priorities.

Velocity stacks prefrer still air, not ram air. Two completely different subjects.

The press and BMW claimed that the square airbox crank vent setup evenly distributed crank vent oil to both cylinders. It does not. They almost entirely favor the left side. Why and how? The vent hose to the left velocity stack does not rise up quite as high as the one for the right stack. It's like plumping: Shit won't go up hill. Yes, I know BMW and the press claimed the late model setup distributes the oil evenly but they don't in fact. Yes, I know ss is about the only source for this info but it is still true.

SS, I think you are talking again in the third person. You should watch that.